Most switch power supplies or linear power supplies have compensation links, an output signal of a compensation link sampling system is also a controlled target amount. By comparing with the reference signal, an error signal is generated to control an output power of a power device, thereby achieving the purpose of controlled voltage type or current type output. During the above process, the compensation link can realize the low frequency and high gain of the circuit and achieve the purpose of accurately controlling the controlled target amount.
A typical compensation link comprises a proportional link and an inertial link and is designed as appropriate parameters according to requirements. In some systems, such as power factor correction circuits, because the line frequency is 50/60 Hz, in order to make the system stable during a power frequency cycle, usually an inertial link with a bandwidth of 10 Hz is needed. To achieve this, the traditional approach is to use a relatively large compensation capacitor, while the capacitance of this compensation capacitor determines that it is difficult to be integrated by the integrated circuit, therefore, the integrated circuit usually needs a dedicated pin to connect the external capacitor to obtain a basic stable error signal within the power frequency cycle. In the above traditional compensation network, there are the following problems: firstly, the compensation capacitor requires cost and occupies space; secondly, the dedicated pin of the integrated circuit also accounts for the system cost; and thirdly, in a high temperature and humidity environment, the external compensation capacitor may leak current on the printed circuit board, which may cause system failure.
Therefore, the existing compensation network technology has the problems of high cost in the power control circuit and low reliability in the power supply.